Database transaction guaranteed commitment

ABSTRACT

An example operation may include one or more of receiving, by a committer node or peer of a blockchain network, a block comprising a lock request that locks a partial state of a smart contract, the lock request comprising a submitter identifier and a lock delay, the committer node or peer configured to process blocks of transactions, the method further comprising, validating the lock request, committing transactions comprising the submitter identifier with no delay, and committing transactions not comprising the submitter identifier after the lock delay.

TECHNICAL FIELD

This application generally relates to using synchronization delays to enhance transaction commitment, and more particularly, to guaranteed transaction commitment in a database.

BACKGROUND

A centralized database stores and maintains data in a single database (e.g., a database server) at one location. This location is often a central computer, for example, a desktop central processing unit (CPU), a server CPU, or a mainframe computer. Information stored on a centralized database is typically accessible from multiple different points. Multiple users or client workstations can work simultaneously on the centralized database, for example, based on a client/server configuration. A centralized database is easy to manage, maintain, and control, especially for purposes of security because of its single location. Within a centralized database, data redundancy is minimized as a single storing place of all data also implies that a given set of data only has one primary record.

However, a centralized database suffers from significant drawbacks. For example, a centralized database has a single point of failure. In particular, if there are no fault-tolerance considerations and a hardware failure occurs (for example a hardware, firmware, and/or a software failure), all data within the database is lost and work of all users is interrupted. In addition, centralized databases are highly dependent on network connectivity. As a result, the slower the connection, the amount of time needed for each database access is increased. Another drawback is the occurrence of bottlenecks when a centralized database experiences high traffic due to a single location. Furthermore, a centralized database provides limited access to data because only one copy of the data is maintained by the database. As a result, multiple devices cannot access the same piece of data at the same time without creating significant problems or risk overwriting stored data. Furthermore, because a database storage system has minimal to no data redundancy, data that is unexpectedly lost is very difficult to retrieve other than through manual operation from back-up storage. As such, what is needed is a solution that overcomes these drawbacks and limitations.

SUMMARY

One example embodiment provides a system that includes a blockchain network, which includes a smart contract, comprising a stored smart contract identifier, and a committer node or peer, configured to process blocks of transactions, the committer node or peer further configured to perform one or more of receive a block comprising a lock request that locks a partial state of the smart contract, the lock request comprising a submitter identifier and a lock delay, validate the lock request; commit transactions comprising the submitter identifier with no delay, and commit transactions not comprising the submitter identifier after the lock delay.

Another example embodiment provides a method that includes one or more of receiving, by a committer node or peer of a blockchain network, a block comprising a lock request that locks a partial state of a smart contract, the lock request comprising a submitter identifier and a lock delay, the committer node or peer configured to process blocks of transactions, the method further comprising, validating the lock request, committing transactions comprising the submitter identifier with no delay, and committing transactions not comprising the submitter identifier after the lock delay.

A further example embodiment provides a non-transitory computer readable medium comprising instructions, that when read by a processor, cause the processor to perform one or more of receiving, by a committer node or peer of a blockchain network, a block comprising a lock request that locks a partial state of a smart contract, the lock request comprising a submitter identifier and a lock delay, the committer node or peer configured to process blocks of transactions, the instructions causing the processor to further perform, validating the lock request, committing transactions comprising the submitter identifier with no delay; and committing transactions not comprising the submitter identifier after the lock delay.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a logic network diagram for synchronizing transactions into delayed blocks, according to example embodiments.

FIG. 1B illustrates a lock request, according to example embodiments.

FIG. 2A illustrates an example blockchain architecture configuration, according to example embodiments.

FIG. 2B illustrates a blockchain transactional flow, according to example embodiments.

FIG. 3A illustrates a permissioned network, according to example embodiments.

FIG. 3B illustrates another permissioned network, according to example embodiments.

FIG. 4 illustrates a system messaging diagram for performing block synchronization in a blockchain, according to example embodiments.

FIG. 5A illustrates an example method of synchronizing transactions for block commitment in a blockchain, according to example embodiments.

FIG. 5B illustrates an example method of ordering transactions in a distributed ledger of a blockchain, according to example embodiments.

FIG. 6A illustrates an example system configured to perform one or more operations described herein, according to example embodiments.

FIG. 6B illustrates another example system configured to perform one or more operations described herein, according to example embodiments.

FIG. 6C illustrates a further example system configured to utilize a smart contract, according to example embodiments.

FIG. 6D illustrates yet another example system configured to utilize a blockchain, according to example embodiments.

FIG. 7A illustrates a process for a new block being added to a distributed ledger, according to example embodiments.

FIG. 7B illustrates contents of a new data block, according to example embodiments.

FIG. 7C illustrates a blockchain for digital content, according to example embodiments.

FIG. 7D illustrates a block which may represent the structure of blocks in the blockchain, according to example embodiments.

FIG. 8 illustrates an example system that supports one or more of the example embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of at least one of a method, apparatus, non-transitory computer readable medium and system, as represented in the attached figures, is not intended to limit the scope of the application as claimed but is merely representative of selected embodiments.

The instant features, structures, or characteristics as described throughout this specification may be combined or removed in any suitable manner in one or more embodiments. For example, the usage of the phrases “example embodiments”, “some embodiments”, or other similar language, throughout this specification refers to the fact that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment. Thus, appearances of the phrases “example embodiments”, “in some embodiments”, “in other embodiments”, or other similar language, throughout this specification do not necessarily all refer to the same group of embodiments, and the described features, structures, or characteristics may be combined or removed in any suitable manner in one or more embodiments.

In addition, while the term “message” may have been used in the description of embodiments, the application may be applied to many types of networks and data. Furthermore, while certain types of connections, messages, and signaling may be depicted in exemplary embodiments, the application is not limited to a certain type of connection, message, and signaling.

Example embodiments provide methods, systems, components, non-transitory computer readable media, devices, and/or networks, which provide database transaction guaranteed commitment.

In one embodiment the application utilizes a decentralized database (such as a blockchain) that is a distributed storage system, which includes multiple nodes that communicate with each other. The decentralized database includes an append-only immutable data structure resembling a distributed ledger capable of maintaining records between mutually untrusted parties. The untrusted parties are referred to herein as peers or peer nodes. Each peer maintains a copy of the database records and no single peer can modify the database records without a consensus being reached among the distributed peers. For example, the peers may execute a consensus protocol to validate blockchain storage transactions, group the storage transactions into blocks, and build a hash chain over the blocks. This process forms the ledger by ordering the storage transactions, as is necessary, for consistency. In various embodiments, a permissioned and/or a permissionless blockchain can be used. In a public or permission-less blockchain, anyone can participate without a specific identity. Public blockchains often involve native cryptocurrency and use consensus based on various protocols such as Proof of Work (PoW). On the other hand, a permissioned blockchain database provides secure interactions among a group of entities which share a common goal but which do not fully trust one another, such as businesses that exchange funds, goods, information, and the like.

This application can utilize a blockchain that operates arbitrary, programmable logic, tailored to a decentralized storage scheme and referred to as “smart contracts” or “chaincodes.” In some cases, specialized chaincodes may exist for management functions and parameters which are referred to as system chaincode. The application can further utilize smart contracts that are trusted distributed applications which leverage tamper-proof properties of the blockchain database and an underlying agreement between nodes, which is referred to as an endorsement or endorsement policy. Blockchain transactions associated with this application can be “endorsed” before being committed to the blockchain while transactions, which are not endorsed, are disregarded. An endorsement policy allows chaincode to specify endorsers for a transaction in the form of a set of peer nodes that are necessary for endorsement. When a client sends the transaction to the peers specified in the endorsement policy, the transaction is executed to validate the transaction. After validation, the transactions enter an ordering phase in which a consensus protocol is used to produce an ordered sequence of endorsed transactions grouped into blocks.

This application can utilize nodes that are the communication entities of the blockchain system. A “node” may perform a logical function in the sense that multiple nodes of different types can run on the same physical server. Nodes are grouped in trust domains and are associated with logical entities that control them in various ways. Nodes may include different types, such as a client or submitting-client node which submits a transaction-invocation to an endorser (e.g., peer), and broadcasts transaction-proposals to an ordering service (e.g., ordering node). Another type of node is a peer node which can receive client submitted transactions, commit the transactions and maintain a state and a copy of the ledger of blockchain transactions. Peers can also have the role of an endorser, although it is not a requirement. An ordering-service-node or orderer is a node running the communication service for all nodes, and which implements a delivery guarantee, such as a broadcast to each of the peer nodes in the system when committing transactions and modifying a world state of the blockchain, which is another name for the initial blockchain transaction which normally includes control and setup information.

This application can utilize a ledger that is a sequenced, tamper-resistant record of all state transitions of a blockchain. State transitions may result from chaincode invocations (i.e., transactions) submitted by participating parties (e.g., client nodes, ordering nodes, endorser nodes, peer nodes, etc.). Each participating party (such as a peer node) can maintain a copy of the ledger. A transaction may result in a set of asset key-value pairs being committed to the ledger as one or more operands, such as creates, updates, deletes, and the like. The ledger includes a blockchain (also referred to as a chain) which is used to store an immutable, sequenced record in blocks. The ledger also includes a state database which maintains a current state of the blockchain.

This application can utilize a chain that is a transaction log which is structured as hash-linked blocks, and each block contains a sequence of N transactions where N is equal to or greater than one. The block header includes a hash of the block's transactions, as well as a hash of the prior block's header. In this way, all transactions on the ledger may be sequenced and cryptographically linked together. Accordingly, it is not possible to tamper with the ledger data without breaking the hash links. A hash of a most recently added blockchain block represents every transaction on the chain that has come before it, making it possible to ensure that all peer nodes are in a consistent and trusted state. The chain may be stored on a peer node file system (i.e., local, attached storage, cloud, etc.), efficiently supporting the append-only nature of the blockchain workload.

The current state of the immutable ledger represents the latest values for all keys that are included in the chain transaction log. Since the current state represents the latest key values known to a channel, it is sometimes referred to as a world state. Chaincode invocations execute transactions against the current state data of the ledger. To make these chaincode interactions efficient, the latest values of the keys may be stored in a state database. The state database may be simply an indexed view into the chain's transaction log, it can therefore be regenerated from the chain at any time. The state database may automatically be recovered (or generated if needed) upon peer node startup, and before transactions are accepted.

Some benefits of the instant solutions described and depicted herein include the following: The locking request is not a normal transaction, and it does not require endorsement and a read-write set. Instead, it is sent directly to the block generators. Additionally, the locking is settled in the ledger, validated, and taken into account by committers in an autonomous way. Furthermore, when acting as endorsers, they do not endorse incoming transactions from clients that do not benefit from the acquired lock. The locking is added on top of existing optimistic concurrency control and can be used in conjunction with it for the same smart contract.

The present application addresses a problem in blockchain platforms, in which transactions are executed by several nodes or peers potentially in different host providers. The present application a solution when each blockchain transaction is required to be endorsed by multiples nodes before it be committed. The solution is required when the network is scattered in multiple regions, when transactions may be subject to different network or processing delays. Therefore, acquiring a partial lock to give enough time for the subset of endorsing nodes or peers to synchronize and endorse the transaction under the same conditions is beneficial to prevent transaction invalidation due to another transaction changing a smart contract state and thus invalidating or even blocking some transactions requiring the endorsement by slower endorsers. The locking is to guarantee the endorsing phase can be completed.

Partial locks may be included in blocks. In a preferred embodiment, as a transaction in which content provides the information associated to the locking being requested (e.g. smart contract) and a subset of keys to be protected, participants which may be able to take advantage of the lock, timeout, etc. Such transactions may be processed by nodes or peers in the network, and the lock needs to be activated and released accordingly.

In blockchain networks, endorsed transactions can sometimes be invalidated due to an invalidated read set, when another committed transaction updated at least one of the keys included in the read-set. In some cases, this may prevent the commitment of endorsed transactions involving nodes or peers with high synchronization delays. In other cases, this may also prevent the commitment of endorsed transactions having low synchronization delays but a high frequency of transactions involving the same smart-contract. Cancelled commitment of endorsed transactions generates a waste of time and resources, and invalidated transactions need to be reattempted without further guarantee of success (if all the endorsements do not complete when expected). Additionally, in some cases blockchain clients may be required to use a specific subset of endorsers and not only those with similar endorsement delays. Thus, there exists a need to mitigate the situation and ensure the transactions will not be invalidated due to delayed endorsement.

FIG. 1A illustrates a logic network diagram for synchronizing transactions into delayed blocks, according to example embodiments. Referring to FIG. 1A, the network 100 may be a public blockchain network or a permissioned blockchain network, such as a Hyperledger Blockchain network.

Blockchain network 100 includes blockchain nodes or peers 104, which initiate various types of blockchain transactions 112, including blockchain transactions that include a lock request 128. Other nodes or peers (not shown) are responsible for endorsement of blockchain transactions 112, and these endorsing nodes or peers may be widely geographically dispersed. Being widely dispersed may mean that endorsements from some endorsement nodes or peers may be delayed relative to other endorsement nodes or peers.

Once endorsements have been received, a committer or orderer node or peer 108 (referred hereinafter as a committer node or peer, for simplicity) gathers transactions into new blocks 140 for a blockchain 136. The blockchain 136 may include any number of blocks 140, from a first block 140A (sometimes referred to as a genesis block) through more recent blocks 140L, 140M, and 140N.

The committer node or peer 108 utilizes a smart contract or chaincode 116 to make decisions related to validating or not validating lock requests 128. The blockchain network 100 may include one or more smart contracts 116, and each smart contract 116 that may require locking of a partial state includes a stored smart contract identifier 120 and keys 124. The stored smart contract identifier 120 uniquely identifies each smart contract 116 from other smart contracts 116. Keys 124 are used to validate blockchain nodes or peers 104 that initiate blockchain transactions 112 including those that include lock requests 128. In one embodiment, whenever a blockchain client experiences transaction invalidations, it can request a lock.

Committer nodes or peers 108 validate lock requests 128 when processing the next block 140. If a lock request 128 is valid (credentials, smart contract identifier 120, keys 124, and synchronization delay 144 may be checked), it will not commit transactions for that smart contract 116 from clients that do not benefit from from the acquired lock and may update at least a key 124 of the lock. However, blockchain transactions submitted from clients that do benefit from the lock will be committed to the blockchain 136. Committer peers 108 when acting as endorsing peers will not endorse transactions 112 that do not bypass the lock. Transactions 112 that do not bypass the lock are transactions 112 that modify state protected by an approved and an active lock submitted by participants that do not benefit from it.

Advantageously, the disclosed improvement allows blockchain nodes or peers 104 to avoid the uncertainty of submitting a blockchain transaction 112 while conventional approaches may still be used, even for the same smart contract 116. Time and computing resources may be optimized, and blockchain transactions 112 requiring endorser nodes or peers having high synchronization delays 144 may be committed to the blockchain 136 without additional invalidation/retry operations.

The present application provides a novel locking mechanism for blockchain platforms with endorsed transactions. A lock request 128 specifies a smart contract 116, a subset of keys 124, a synchronization delay 144, and one or more client or organization. Validated locks may be settled in a shared ledger of the blockchain network 100 as another transaction. Locks do not include a read-write set or are subject to endorsing policies that transactions involving smart contract 116 execution may require. Locking is settled in the shared ledger, validated, and taken into account by committers 108 in an autonomous way.

FIG. 1B illustrates a lock request, 128 according to example embodiments. Referring to FIG. 1B, lock requests 128 include a submitter ID or identifier 148. The submitter identifier 148 identifies a client, group of clients, or organization that the lock request 128 applies to. Blockchain node or peers 104 may represent organizations of multiple blockchain nodes or peers 104 that submit blockchain transactions 112 and lock requests 128. Therefore, the submitter ID 148 identifies a client or organization that can benefit from the lock request 128 Committers 108 will consider transactions 112 submitted by clients or organizations that benefit the approved lock 148 and will ignore (invalidate) transactions 112 submitted from others. In some embodiments, a lock request 128 may be sent to block generators directly, may not require endorsement, and a smart contract 120 may specify an upper bound for synchronization delays 144.

Lock requests 128 also include a smart contract ID 152. The smart contract ID or identifier 152 uniquely identifies a smart contract 116 that is used to qualify lock requests 128. Thus, part of lock request 128 validation is matching the smart contract ID 152 with an active smart contract 116.

Lock requests 128 also include a subset of keys 156. A lock may include information describing what cannot be changed. In Hyperledger Fabric blockchain networks 100, this may include a subset of keys 124 that correspond to the state of a smart contract 116. In some cases, the keys 124 may be modified by one or more blockchain transactions 112. The locking would prevent undesired blockchain transactions 112 from modifying such keys 124 (i.e., avoid including them in write sets of other blockchain transactions 112, and other blockchain transactions 112 submitted by participants not included in the lock request 128).

Finally, lock requests 128 include a lock delay 144. The lock delay 144 is an amount of time or a number of blocks that commitment for non-qualifying endorsed transactions need to be delayed. Non-qualified endorsed transactions are transactions from other blockchain nodes or peers 104 that do not correspond to the submitted ID 148. By specifying a lock delay 144, other transactions that may modify keys 156 are delayed and thereby prevented from modifying keys. For example, transactions 112 from other blockchain nodes or peers 104 that do not correspond to the submitter ID 148 may be delayed from commitment to block 140L to block 140N.

FIG. 2A illustrates a blockchain architecture configuration 200, according to example embodiments. Referring to FIG. 2A, the blockchain architecture 200 may include certain blockchain elements, for example, a group of blockchain nodes 202. The blockchain nodes 202 may include one or more nodes 204-210 (these four nodes are depicted by example only). These nodes participate in a number of activities, such as blockchain transaction addition and validation process (consensus). One or more of the blockchain nodes 204-210 may endorse transactions based on endorsement policy and may provide an ordering service for all blockchain nodes in the architecture 200. A blockchain node may initiate a blockchain authentication and seek to write to a blockchain immutable ledger stored in blockchain layer 216, a copy of which may also be stored on the underpinning physical infrastructure 214. The blockchain configuration may include one or more applications 224 which are linked to application programming interfaces (APIs) 222 to access and execute stored program/application code 220 (e.g., chaincode, smart contracts, etc.) which can be created according to a customized configuration sought by participants and can maintain their own state, control their own assets, and receive external information. This can be deployed as a transaction and installed, via appending to the distributed ledger, on all blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers of blockchain data, services (e.g., cryptographic trust services, virtual execution environment, etc.), and underpinning physical computer infrastructure that may be used to receive and store new transactions and provide access to auditors which are seeking to access data entries. The blockchain layer 216 may expose an interface that provides access to the virtual execution environment necessary to process the program code and engage the physical infrastructure 214. Cryptographic trust services 218 may be used to verify transactions such as asset exchange transactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process and execute program/application code 220 via one or more interfaces exposed, and services provided, by blockchain platform 212. The code 220 may control blockchain assets. For example, the code 220 can store and transfer data, and may be executed by nodes 204-210 in the form of a smart contract and associated chaincode with conditions or other code elements subject to its execution. As a non-limiting example, smart contracts may be created to execute reminders, updates, and/or other notifications subject to the changes, updates, etc. The smart contracts can themselves be used to identify rules associated with authorization and access requirements and usage of the ledger. For example, the information 226 may include a lock request to lock a partial state of a smart contract. The lock request 226 may be processed by one or more processing entities (e.g., virtual machines) included in the blockchain layer 216. The result 228 may include one or more synchronized blocks. The physical infrastructure 214 may be utilized to retrieve any of the data or information described herein.

A smart contract may be created via a high-level application and programming language, and then written to a block in the blockchain. The smart contract may include executable code which is registered, stored, and/or replicated with a blockchain (e.g., distributed network of blockchain peers). A transaction is an execution of the smart contract code which can be performed in response to conditions associated with the smart contract being satisfied. The executing of the smart contract may trigger a trusted modification(s) to a state of a digital blockchain ledger. The modification(s) to the blockchain ledger caused by the smart contract execution may be automatically replicated throughout the distributed network of blockchain peers through one or more consensus protocols.

The smart contract may write data to the blockchain in the format of key-value pairs. Furthermore, the smart contract code can read the values stored in a blockchain and use them in application operations. The smart contract code can write the output of various logic operations into the blockchain. The code may be used to create a temporary data structure in a virtual machine or other computing platform. Data written to the blockchain can be public and/or can be encrypted and maintained as private. The temporary data that is used/generated by the smart contract is held in memory by the supplied execution environment, then deleted once the data needed for the blockchain is identified.

A chaincode may include the code interpretation of a smart contract, with additional features. As described herein, the chaincode may be program code deployed on a computing network, where it is executed and validated by chain validators together during a consensus process. The chaincode receives a hash and retrieves from the blockchain a hash associated with the data template created by use of a previously stored feature extractor. If the hashes of the hash identifier and the hash created from the stored identifier template data match, then the chaincode sends an authorization key to the requested service. The chaincode may write to the blockchain data associated with the cryptographic details.

FIG. 2B illustrates an example of a blockchain transactional flow 250 between nodes of the blockchain in accordance with an example embodiment. Referring to FIG. 2B, the transaction flow may include a transaction proposal 291 sent by an application client node 260 to an endorsing peer node 281. The endorsing peer 281 may verify the client signature and execute a chaincode function to initiate the transaction. The output may include the chaincode results, a set of key/value versions that were read in the chaincode (read set), and the set of keys/values that were written in chaincode (write set). The proposal response 292 is sent back to the client 260 along with an endorsement signature, if approved. The client 260 assembles the endorsements into a transaction payload 293 and broadcasts it to an ordering service node 284. The ordering service node 284 then delivers ordered transactions as blocks to all peers 281-283 on a channel. Before committal to the blockchain, each peer 281-283 may validate the transaction. For example, the peers may check the endorsement policy to ensure that the correct allotment of the specified peers have signed the results and authenticated the signatures against the transaction payload 293.

Referring again to FIG. 2B, the client node 260 initiates the transaction 291 by constructing and sending a request to the peer node 281, which is an endorser. The client 260 may include an application leveraging a supported software development kit (SDK), which utilizes an available API to generate a transaction proposal. The proposal is a request to invoke a chaincode function so that data can be read and/or written to the ledger (i.e., write new key value pairs for the assets). The SDK may serve as a shim to package the transaction proposal into a properly architected format (e.g., protocol buffer over a remote procedure call (RPC)) and take the client's cryptographic credentials to produce a unique signature for the transaction proposal.

In response, the endorsing peer node 281 may verify (a) that the transaction proposal is well formed, (b) the transaction has not been submitted already in the past (replay-attack protection), (c) the signature is valid, and (d) that the submitter (client 260, in the example) is properly authorized to perform the proposed operation on that channel. The endorsing peer node 281 may take the transaction proposal inputs as arguments to the invoked chaincode function. The chaincode is then executed against a current state database to produce transaction results including a response value, read set, and write set. However, no updates are made to the ledger at this point. In 292, the set of values, along with the endorsing peer node's 281 signature is passed back as a proposal response 292 to the SDK of the client 260 which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies the endorsing peers signatures and compares the proposal responses to determine if the proposal response is the same. If the chaincode only queried the ledger, the application would inspect the query response and would typically not submit the transaction to the ordering node service 284. If the client application intends to submit the transaction to the ordering node service 284 to update the ledger, the application determines if the specified endorsement policy has been fulfilled before submitting (i.e., did all peer nodes necessary for the transaction endorse the transaction). Here, the client may include only one of multiple parties to the transaction. In this case, each client may have their own endorsing node, and each endorsing node will need to endorse the transaction. The architecture is such that even if an application selects not to inspect responses or otherwise forwards an unendorsed transaction, the endorsement policy will still be enforced by peers and upheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assembles endorsements into a transaction and broadcasts the transaction proposal and response within a transaction message to the ordering node 284. The transaction may contain the read/write sets, the endorsing peers signatures and a channel ID. The ordering node 284 does not need to inspect the entire content of a transaction in order to perform its operation, instead the ordering node 284 may simply receive transactions from all channels in the network, order them chronologically by channel, and create blocks of transactions per channel.

The blocks of the transaction are delivered from the ordering node 284 to all peer nodes 281-283 on the channel. The transactions 294 within the block are validated to ensure any endorsement policy is fulfilled and to ensure that there have been no changes to ledger state for read set variables since the read set was generated by the transaction execution. Transactions in the block are tagged as being valid or invalid. Furthermore, in step 295 each peer node 281-283 appends the block to the channel's chain, and for each valid transaction the write sets are committed to current state database. An event is emitted, to notify the client application that the transaction (invocation) has been immutably appended to the chain, as well as to notify whether the transaction was validated or invalidated.

FIG. 3A illustrates an example of a permissioned blockchain network 300, which features a distributed, decentralized peer-to-peer architecture. In this example, a blockchain user 302 may initiate a transaction to the permissioned blockchain 304. In this example, the transaction can be a deploy, invoke, or query, and may be issued through a client-side application leveraging an SDK, directly through an API, etc. Networks may provide access to a regulator 306, such as an auditor. A blockchain network operator 308 manages member permissions, such as enrolling the regulator 306 as an “auditor” and the blockchain user 302 as a “client”. An auditor could be restricted only to querying the ledger whereas a client could be authorized to deploy, invoke, and query certain types of chaincode.

A blockchain developer 310 can write chaincode and client-side applications. The blockchain developer 310 can deploy chaincode directly to the network through an interface. To include credentials from a traditional data source 312 in chaincode, the developer 310 could use an out-of-band connection to access the data. In this example, the blockchain user 302 connects to the permissioned blockchain 304 through a peer node 314. Before proceeding with any transactions, the peer node 314 retrieves the user's enrollment and transaction certificates from a certificate authority 316, which manages user roles and permissions. In some cases, blockchain users must possess these digital certificates in order to transact on the permissioned blockchain 304. Meanwhile, a user attempting to utilize chaincode may be required to verify their credentials on the traditional data source 312. To confirm the user's authorization, chaincode can use an out-of-band connection to this data through a traditional processing platform 318.

FIG. 3B illustrates another example of a permissioned blockchain network 320, which features a distributed, decentralized peer-to-peer architecture. In this example, a blockchain user 322 may submit a transaction to the permissioned blockchain 324. In this example, the transaction can be a deploy, invoke, or query, and may be issued through a client-side application leveraging an SDK, directly through an API, etc. Networks may provide access to a regulator 326, such as an auditor. A blockchain network operator 328 manages member permissions, such as enrolling the regulator 326 as an “auditor” and the blockchain user 322 as a “client”. An auditor could be restricted only to querying the ledger whereas a client could be authorized to deploy, invoke, and query certain types of chaincode.

A blockchain developer 330 writes chaincode and client-side applications. The blockchain developer 330 can deploy chaincode directly to the network through an interface. To include credentials from a traditional data source 332 in chaincode, the developer 330 could use an out-of-band connection to access the data. In this example, the blockchain user 322 connects to the network through a peer node 334. Before proceeding with any transactions, the peer node 334 retrieves the user's enrollment and transaction certificates from the certificate authority 336. In some cases, blockchain users must possess these digital certificates in order to transact on the permissioned blockchain 324. Meanwhile, a user attempting to utilize chaincode may be required to verify their credentials on the traditional data source 332. To confirm the user's authorization, chaincode can use an out-of-band connection to this data through a traditional processing platform 338.

FIG. 4 illustrates a system messaging diagram 400 for performing block synchronization in a blockchain, according to example embodiments. Referring to FIG. 4, the system diagram 400 includes a client or blockchain peer 410, a committer node or peer 420, and a blockchain network 430. The client or blockchain peer 410 issued various types of blockchain transactions to the blockchain network 430, and may wish to issue lock requests in order to make sure that endorsement completes without needing to reissue transactions.

The client or blockchain peer 410 generates a transaction 415 that may include a lock request. The blockchain transaction 416 is issued to the blockchain network 430, and a lock request 417 within the blockchain transaction 416 is provided to the committer node or peer 420.

The committer node or peer 420 then performs several operations to validate the received lock request 417. First, the client or blockchain peer 410 that submitted the lock request 417 is verified to make sure it is valid within the blockchain network 425. Next, the committer node or peer 420 verifies a smart contract identifier provided in the lock request matches a stored smart contract identifier for a smart contract 435. Assuming the identifiers match and the submitting client or blockchain peer is valid, the committed node or peer 420 next verifies the submitting client or blockchain peer 410 is authorized/allowed to submit the lock request for the specified smart contract 440. Finally, the committer node or peer 420 determines if other lock requests for the same smart contract are active 445. It there are already active lock requests for the smart contract, the committer node or peer 420 provides an invalidated transaction 446 back to the submitting client or blockchain peer 410. At that point, the client or blockchain peer 410 may elect to reissue the blockchain transaction 455—and the committer node or peer 420 then repeats steps 425-445 to validate the lock request.

Once the committer node or peer 420 validates the lock request 417, the committer node or peer applies a synchronization delay 460 to a block containing the blockchain transaction 416. The synchronization delay 460 is specified within the lock request 417, and specifies a time delay or a number of blocks to delay.

At some point, the blockchain network 430 endorses the transaction 450 using a set of endorser nodes or peers specified in a smart contract. The endorsed transaction 451 is then provided to the blockchain node or peer 410 as well as the committer node or peer 420 to include in a new block for the blockchain.

With the endorsed transaction 451 received and the synchronization delay 460 applied, the committer node or peer 420 next commits the transaction 465 and generates a new block 466 containing the blockchain transaction 416. The blockchain network receives the block 466 and commits the block to the shared ledger 470 for the blockchain network.

FIG. 5A illustrates a flow diagram 500 of an example method of synchronizing transactions for block commitment in a blockchain, according to example embodiments. Referring to FIG. 5A, the method 500 may include receiving a lock request 504 from a client or blockchain node or peer. In some embodiments, the submitter may be an organization including one or more clients or blockchain nodes/peers.

At block 508, a committer node or peer validates the lock request. Validating the lock request may include the approval steps described in detail with respect to FIG. 4, and may include other verification steps, including but not limited to credential verification, key verification, and identifier verification.

At block 512, the committer node or peer implements a lock delay specified in the lock request. The lock delay may specify an amount of time or a number of blocks by which a block commitment to a blockchain is delayed. This delay may be required in order to accommodate delayed endorsements from distant endorser nodes or peers of the blockchain network. The lock delay applies to transactions received from blockchain nodes or peers that do not have an active lock request. By delaying block commitment, keys that may be used for transactions for the lock request do not get modified by other transactions having one or more keys in common with the lock request transactions. Modified keys may result in transaction invalidations. Invalidated transactions may require re-issue by a submitting node, peer, or organization, which unnecessarily consumes blockchain network resources and bandwidth.

At block 516, the committer node or peer commits transactions without delay that correspond to an active lock request, and delays commitment of transactions that do not correspond to an active lock.

At block 520, the blockchain network processes blockchain transactions based on active locks in-place to smart contracts. The blockchain network commits blocks to a shared and immutable ledger.

FIG. 5B illustrates a flow diagram 550 of an example method of ordering transactions in a distributed ledger of a blockchain, according to example embodiments. Referring to FIG. 5B, the method 550 provides for ordering transactions in a distributed ledger in accordance with some embodiments, and may include one or more of the following steps.

The method may be implemented as a set of computer readable instructions that are executed at a network node. Briefly, the method 550 includes synthesizing a proposed block, ordering transactions within the proposed block based on their corresponding timestamps, transmitting the block proposal, and storing the proposed block in the distributed ledger in response to receiving an indication that the block proposal has been accepted.

As represented by block 554, in various implementations, the method 550 may include storing a transaction in association with a timestamp in a transaction buffer. In various implementations, the method 550 may include storing the transaction in the transaction buffer after receiving a transaction request from a client device. In various implementations, the method 550 may include storing the transaction in the transaction buffer in response to validating the transaction. For example, in some implementations, the method 550 may include storing the transaction in the transaction buffer in response to determining that the transaction satisfies a validation criterion (e.g., the transaction includes sufficient transaction data to be processed).

As represented by block 558, in various implementations, the method 550 may include synthesizing a block proposal that indicates (e.g., includes) a proposed block that includes transactions that are stored in the transaction buffer.

In various implementations, the method 550 may include selecting transactions from the transaction buffer based on the timestamps associated with the transactions. For example, in some implementations, the method 450 includes selecting transactions that are associated with the oldest timestamps. In some examples, the method 550 may include including transactions into the proposed block on a first-in-first-out (FIFO) basis. In some implementations, the method 550 may include selecting transactions that are associated with later timestamps. In some examples, the method 550 may include transactions into the proposed block on a last-in-first-out (LIFO) basis.

As represented by block 562, in various implementations, the method 550 may include ordering the transactions within the proposed block based on the timestamps associated with the transactions. For example, in some implementations, the method 550 may include ordering the transactions such that transactions with earlier timestamps are listed towards the beginning of the proposed block, and transactions with later timestamps are listed towards the end of the proposed block. In some implementations, the method 550 may include ordering the transactions such that transactions with later timestamps are listed towards the beginning of the proposed block, and transactions with earlier timestamps are listed towards the end of the proposed block.

As represented by block 566, in various implementations, the method 550 may include transmitting the block proposal to other network nodes in the distributed ledger system. In some implementations, the method 550 may include utilizing a cryptographic hash function (e.g., SHA-256) to generate a digest. In some examples, the method 550 may include inputting the proposed block and a number (e.g., a random number or a pseudo-random number) into the cryptographic hash function to generate the digest. In some implementations, the method 550 may include determining whether the digest satisfies a digest criterion. In some examples, the digest criterion specifies that the digest include a particular number of leading zeros. In such examples, the method 550 may include determining whether the digest includes the particular number of leading zeros. In various implementations, the method 550 may include transmitting the block proposal to the other network nodes in response to determining that the digest satisfies the digest criterion. In various implementations, the method 550 may include determining that the digest does not satisfy the digest criteria and generating a new digest by selecting a different number (e.g., by incrementing the previous number).

As represented by block 570, in various implementations, the method 450 may include receiving an indication that indicates whether the block proposal has been accepted or rejected. In some implementations, the method 550 may include receiving an indication that indicates that the block proposal has been accepted. In some implementations, the method 550 may include receiving an indication that indicates that the block proposal has been rejected.

As represented by block 574, in various implementations, the method 550 may include storing the proposed block in the distributed ledger. In some embodiments, the method 550 may include purging the transactions that were in the proposed block from the transaction buffer. In some embodiments, the method 550 may include discarding the proposed block. In some implementations, the method 550 may include, at least another network node (e.g., at each network node) that maintains the distributed ledger and synthesizes a timestamp for the transaction. In some examples, the arrival time of the transaction indicator is different for different network nodes. For example, some network nodes receive the transaction indicator sooner than other network nodes. As such, in some examples, before a transaction is recorded in the distributed ledger, the transaction is associated with multiple timestamps. However, in some implementations, once the transaction is recorded in the distributed ledger, the transaction is associated with the timestamp synthesized by the network node that recorded the transaction in the distributed ledger.

FIG. 6A illustrates an example system 600 that includes a physical infrastructure 610 configured to perform various operations according to example embodiments. Referring to FIG. 6A, the physical infrastructure 610 includes a module 612 and a module 614. The module 614 includes a blockchain 620 and a smart contract 630 (which may reside on the blockchain 620), that may execute any of the operational steps 608 (in module 612) included in any of the example embodiments. The steps/operations 608 may include one or more of the embodiments described or depicted and may represent output or written information that is written or read from one or more smart contracts 630 and/or blockchains 620. The physical infrastructure 610, the module 612, and the module 614 may include one or more computers, servers, processors, memories, and/or wireless communication devices. Further, the module 612 and the module 614 may be a same module.

FIG. 6B illustrates another example system 640 configured to perform various operations according to example embodiments. Referring to FIG. 6B, the system 640 includes a module 612 and a module 614. The module 614 includes a blockchain 620 and a smart contract 630 (which may reside on the blockchain 620), that may execute any of the operational steps 608 (in module 612) included in any of the example embodiments. The steps/operations 608 may include one or more of the embodiments described or depicted and may represent output or written information that is written or read from one or more smart contracts 630 and/or blockchains 620. The physical infrastructure 610, the module 612, and the module 614 may include one or more computers, servers, processors, memories, and/or wireless communication devices. Further, the module 612 and the module 614 may be a same module.

FIG. 6C illustrates an example system configured to utilize a smart contract configuration among contracting parties and a mediating server configured to enforce the smart contract terms on the blockchain according to example embodiments. Referring to FIG. 6C, the configuration 650 may represent a communication session, an asset transfer session or a process or procedure that is driven by a smart contract 630 which explicitly identifies one or more user devices 652 and/or 656. The execution, operations and results of the smart contract execution may be managed by a server 654. Content of the smart contract 630 may require digital signatures by one or more of the entities 652 and 656 which are parties to the smart contract transaction. The results of the smart contract execution may be written to a blockchain 620 as a blockchain transaction. The smart contract 630 resides on the blockchain 620 which may reside on one or more computers, servers, processors, memories, and/or wireless communication devices.

FIG. 6D illustrates a system 660 including a blockchain, according to example embodiments. Referring to the example of FIG. 6D, an application programming interface (API) gateway 662 provides a common interface for accessing blockchain logic (e.g., smart contract 630 or other chaincode) and data (e.g., distributed ledger, etc.). In this example, the API gateway 662 is a common interface for performing transactions (invoke, queries, etc.) on the blockchain by connecting one or more entities 652 and 656 to a blockchain peer (i.e., server 654). Here, the server 654 is a blockchain network peer component that holds a copy of the world state and a distributed ledger allowing clients 652 and 656 to query data on the world state as well as submit transactions into the blockchain network where, depending on the smart contract 630 and endorsement policy, endorsing peers will run the smart contracts 630.

The above embodiments may be implemented in hardware, in a computer program executed by a processor, in firmware, or in a combination of the above. A computer program may be embodied on a computer readable medium, such as a storage medium. For example, a computer program may reside in random access memory (“RAM”), flash memory, read-only memory (“ROM”), erasable programmable read-only memory (“EPROM”), electrically erasable programmable read-only memory (“EEPROM”), registers, hard disk, a removable disk, a compact disk read-only memory (“CD-ROM”), or any other form of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such that the processor may read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an application specific integrated circuit (“ASIC”). In the alternative, the processor and the storage medium may reside as discrete components.

FIG. 7A illustrates a process 700 of a new block being added to a distributed ledger 720, according to example embodiments, and FIG. 7B illustrates contents of a new data block structure 730 for blockchain, according to example embodiments. Referring to FIG. 7A, clients (not shown) may submit transactions to blockchain nodes 711, 712, and/or 713. Clients may be instructions received from any source to enact activity on the blockchain 720. As an example, clients may be applications that act on behalf of a requester, such as a device, person or entity to propose transactions for the blockchain. The plurality of blockchain peers (e.g., blockchain nodes 711, 712, and 713) may maintain a state of the blockchain network and a copy of the distributed ledger 720. Different types of blockchain nodes/peers may be present in the blockchain network including endorsing peers which simulate and endorse transactions proposed by clients and committing peers which verify endorsements, validate transactions, and commit transactions to the distributed ledger 720. In this example, the blockchain nodes 711, 712, and 713 may perform the role of endorser node, committer node, or both.

The distributed ledger 720 includes a blockchain which stores immutable, sequenced records in blocks, and a state database 724 (current world state) maintaining a current state of the blockchain 722. One distributed ledger 720 may exist per channel and each peer maintains its own copy of the distributed ledger 720 for each channel of which they are a member. The blockchain 722 is a transaction log, structured as hash-linked blocks where each block contains a sequence of N transactions. Blocks may include various components such as shown in FIG. 7B. The linking of the blocks (shown by arrows in FIG. 7A) may be generated by adding a hash of a prior block's header within a block header of a current block. In this way, all transactions on the blockchain 722 are sequenced and cryptographically linked together preventing tampering with blockchain data without breaking the hash links. Furthermore, because of the links, the latest block in the blockchain 722 represents every transaction that has come before it. The blockchain 722 may be stored on a peer file system (local or attached storage), which supports an append-only blockchain workload.

The current state of the blockchain 722 and the distributed ledger 722 may be stored in the state database 724. Here, the current state data represents the latest values for all keys ever included in the chain transaction log of the blockchain 722. Chaincode invocations execute transactions against the current state in the state database 724. To make these chaincode interactions extremely efficient, the latest values of all keys are stored in the state database 724. The state database 724 may include an indexed view into the transaction log of the blockchain 722, it can therefore be regenerated from the chain at any time. The state database 724 may automatically get recovered (or generated if needed) upon peer startup, before transactions are accepted.

Endorsing nodes receive transactions from clients and endorse the transaction based on simulated results. Endorsing nodes hold smart contracts which simulate the transaction proposals. When an endorsing node endorses a transaction, the endorsing nodes creates a transaction endorsement which is a signed response from the endorsing node to the client application indicating the endorsement of the simulated transaction. The method of endorsing a transaction depends on an endorsement policy which may be specified within chaincode. An example of an endorsement policy is “the majority of endorsing peers must endorse the transaction”. Different channels may have different endorsement policies. Endorsed transactions are forward by the client application to ordering service 710.

The ordering service 710 accepts endorsed transactions, orders them into a block, and delivers the blocks to the committing peers. For example, the ordering service 710 may initiate a new block when a threshold of transactions has been reached, a timer times out, or another condition. In the example of FIG. 7A, blockchain node 712 is a committing peer that has received a new data new data block 730 for storage on blockchain 720. The first block in the blockchain may be referred to as a genesis block which includes information about the blockchain, its members, the data stored therein, etc.

The ordering service 710 may be made up of a cluster of orderers. The ordering service 710 does not process transactions, smart contracts, or maintain the shared ledger. Rather, the ordering service 710 may accept the endorsed transactions and specifies the order in which those transactions are committed to the distributed ledger 720. The architecture of the blockchain network may be designed such that the specific implementation of ‘ordering’ (e.g., Solo, Kafka, BFT, etc.) becomes a pluggable component.

Transactions are written to the distributed ledger 720 in a consistent order. The order of transactions is established to ensure that the updates to the state database 724 are valid when they are committed to the network. Unlike a cryptocurrency blockchain system (e.g., Bitcoin, etc.) where ordering occurs through the solving of a cryptographic puzzle, or mining, in this example the parties of the distributed ledger 720 may choose the ordering mechanism that best suits that network.

When the ordering service 710 initializes a new data block 730, the new data block 730 may be broadcast to committing peers (e.g., blockchain nodes 711, 712, and 713). In response, each committing peer validates the transaction within the new data block 730 by checking to make sure that the read set and the write set still match the current world state in the state database 724. Specifically, the committing peer can determine whether the read data that existed when the endorsers simulated the transaction is identical to the current world state in the state database 724. When the committing peer validates the transaction, the transaction is written to the blockchain 722 on the distributed ledger 720, and the state database 724 is updated with the write data from the read-write set. If a transaction fails, that is, if the committing peer finds that the read-write set does not match the current world state in the state database 724, the transaction ordered into a block will still be included in that block, but it will be marked as invalid, and the state database 724 will not be updated.

Referring to FIG. 7B, a new data block 730 (also referred to as a data block) that is stored on the blockchain 722 of the distributed ledger 720 may include multiple data segments such as a block header 740, block data 750, and block metadata 760. It should be appreciated that the various depicted blocks and their contents, such as new data block 730 and its contents. shown in FIG. 7B are merely examples and are not meant to limit the scope of the example embodiments. The new data block 730 may store transactional information of N transaction(s) (e.g., 1, 10, 100, 500, 1000, 2000, 3000, etc.) within the block data 750. The new data block 730 may also include a link to a previous block (e.g., on the blockchain 722 in FIG. 7A) within the block header 740. In particular, the block header 740 may include a hash of a previous block's header. The block header 740 may also include a unique block number, a hash of the block data 750 of the new data block 730, and the like. The block number of the new data block 730 may be unique and assigned in various orders, such as an incremental/sequential order starting from zero.

The block data 750 may store transactional information of each transaction that is recorded within the new data block 730. For example, the transaction data may include one or more of a type of the transaction, a version, a timestamp, a channel ID of the distributed ledger 720, a transaction ID, an epoch, a payload visibility, a chaincode path (deploy tx), a chaincode name, a chaincode version, input (chaincode and functions), a client (creator) identify such as a public key and certificate, a signature of the client, identities of endorsers, endorser signatures, a proposal hash, chaincode events, response status, namespace, a read set (list of key and version read by the transaction, etc.), a write set (list of key and value, etc.), a start key, an end key, a list of keys, a Merkel tree query summary, and the like. The transaction data may be stored for each of the N transactions.

In some embodiments, the block data 750 may also store new data 762 which adds additional information to the hash-linked chain of blocks in the blockchain 722. The additional information includes one or more of the steps, features, processes and/or actions described or depicted herein. Accordingly, the new data 762 can be stored in an immutable log of blocks on the distributed ledger 720. Some of the benefits of storing such new data 762 are reflected in the various embodiments disclosed and depicted herein. Although in FIG. 7B the new data 762 is depicted in the block data 750 but could also be located in the block header 740 or the block metadata 760.

The block metadata 760 may store multiple fields of metadata (e.g., as a byte array, etc.). Metadata fields may include signature on block creation, a reference to a last configuration block, a transaction filter identifying valid and invalid transactions within the block, last offset persisted of an ordering service that ordered the block, and the like. The signature, the last configuration block, and the orderer metadata may be added by the ordering service 710. Meanwhile, a committer of the block (such as blockchain node 712) may add validity/invalidity information based on an endorsement policy, verification of read/write sets, and the like. The transaction filter may include a byte array of a size equal to the number of transactions in the block data 750 and a validation code identifying whether a transaction was valid/invalid.

FIG. 7C illustrates an embodiment of a blockchain 770 for digital content in accordance with the embodiments described herein. The digital content may include one or more files and associated information. The files may include media, images, video, audio, text, links, graphics, animations, web pages, documents, or other forms of digital content. The immutable, append-only aspects of the blockchain serve as a safeguard to protect the integrity, validity, and authenticity of the digital content, making it suitable use in legal proceedings where admissibility rules apply or other settings where evidence is taken in to consideration or where the presentation and use of digital information is otherwise of interest. In this case, the digital content may be referred to as digital evidence.

The blockchain may be formed in various ways. In one embodiment, the digital content may be included in and accessed from the blockchain itself. For example, each block of the blockchain may store a hash value of reference information (e.g., header, value, etc.) along the associated digital content. The hash value and associated digital content may then be encrypted together. Thus, the digital content of each block may be accessed by decrypting each block in the blockchain, and the hash value of each block may be used as a basis to reference a previous block. This may be illustrated as follows:

Block 1 Block 2 . . . Block N Hash Value 1 Hash Value 2 Hash Value N Digital Content 1 Digital Content 2 Digital Content N

In one embodiment, the digital content may be not included in the blockchain. For example, the blockchain may store the encrypted hashes of the content of each block without any of the digital content. The digital content may be stored in another storage area or memory address in association with the hash value of the original file. The other storage area may be the same storage device used to store the blockchain or may be a different storage area or even a separate relational database. The digital content of each block may be referenced or accessed by obtaining or querying the hash value of a block of interest and then looking up that has value in the storage area, which is stored in correspondence with the actual digital content. This operation may be performed, for example, a database gatekeeper. This may be illustrated as follows:

$\begin{matrix} \underset{\_}{Blockchain} & \underset{\_}{{Storage}\mspace{14mu} {Area}} \\ {{Block}\mspace{14mu} 1\mspace{14mu} {Hash}\mspace{14mu} {Value}} & {{Block}\mspace{14mu} 1\mspace{14mu} {Hash}\mspace{14mu} {Value}\mspace{14mu} \ldots \mspace{14mu} {Content}} \\ \vdots & \vdots \\ {{Block}\mspace{14mu} N\mspace{14mu} {Hash}\mspace{14mu} {Value}} & {{Block}\mspace{14mu} N\mspace{14mu} {Hash}\mspace{14mu} {Value}\mspace{14mu} \ldots \mspace{14mu} {Content}} \end{matrix}$

In the example embodiment of FIG. 7C, the blockchain 770 includes a number of blocks 778 ₁, 778 ₂, . . . 778 _(N) cryptographically linked in an ordered sequence, where N≥1. The encryption used to link the blocks 778 ₁, 778 ₂, . . . 778 _(N) may be any of a number of keyed or un-keyed Hash functions. In one embodiment, the blocks 778 ₁, 778 ₂, . . . 778 _(N) are subject to a hash function which produces n-bit alphanumeric outputs (where n is 256 or another number) from inputs that are based on information in the blocks. Examples of such a hash function include, but are not limited to, a SHA-type (SHA stands for Secured Hash Algorithm) algorithm, Merkle-Damgard algorithm, HAIFA algorithm, Merkle-tree algorithm, nonce-based algorithm, and a non-collision-resistant PRF algorithm. In another embodiment, the blocks 778 ₁, 778 ₂, . . . , 778 _(N) may be cryptographically linked by a function that is different from a hash function. For purposes of illustration, the following description is made with reference to a hash function, e.g., SHA-2.

Each of the blocks 778 ₁, 778 ₂, . . . , 778 _(N) in the blockchain includes a header, a version of the file, and a value. The header and the value are different for each block as a result of hashing in the blockchain. In one embodiment, the value may be included in the header. As described in greater detail below, the version of the file may be the original file or a different version of the original file.

The first block 778 ₁ in the blockchain is referred to as the genesis block and includes the header 772 ₁, original file 774 ₁, and an initial value 776 ₁. The hashing scheme used for the genesis block, and indeed in all subsequent blocks, may vary. For example, all the information in the first block 778 ₁ may be hashed together and at one time, or each or a portion of the information in the first block 778 ₁ may be separately hashed and then a hash of the separately hashed portions may be performed.

The header 772 ₁ may include one or more initial parameters, which, for example, may include a version number, timestamp, nonce, root information, difficulty level, consensus protocol, duration, media format, source, descriptive keywords, and/or other information associated with original file 774 ₁ and/or the blockchain. The header 772 ₁ may be generated automatically (e.g., by blockchain network managing software) or manually by a blockchain participant. Unlike the header in other blocks 778 ₂ to 778 _(N) in the blockchain, the header 772 ₁ in the genesis block does not reference a previous block, simply because there is no previous block.

The original file 774 ₁ in the genesis block may be, for example, data as captured by a device with or without processing prior to its inclusion in the blockchain. The original file 774 ₁ is received through the interface of the system from the device, media source, or node. The original file 774 ₁ is associated with metadata, which, for example, may be generated by a user, the device, and/or the system processor, either manually or automatically. The metadata may be included in the first block 778 ₁ in association with the original file 774 ₁.

The value 776 ₁ in the genesis block is an initial value generated based on one or more unique attributes of the original file 774 ₁. In one embodiment, the one or more unique attributes may include the hash value for the original file 774 ₁, metadata for the original file 774 ₁, and other information associated with the file. In one implementation, the initial value 776 ₁ may be based on the following unique attributes:

-   -   1) SHA-2 computed hash value for the original file     -   2) originating device ID     -   3) starting timestamp for the original file     -   4) initial storage location of the original file     -   5) blockchain network member ID for software to currently         control the original file and associated metadata

The other blocks 778 ₂ to 778 _(N) in the blockchain also have headers, files, and values. However, unlike the first block 772 ₁, each of the headers 772 ₂ to 772 _(N) in the other blocks includes the hash value of an immediately preceding block. The hash value of the immediately preceding block may be just the hash of the header of the previous block or may be the hash value of the entire previous block. By including the hash value of a preceding block in each of the remaining blocks, a trace can be performed from the Nth block back to the genesis block (and the associated original file) on a block-by-block basis, as indicated by arrows 780, to establish an auditable and immutable chain-of-custody.

Each of the header 772 ₂ to 772 _(N) in the other blocks may also include other information, e.g., version number, timestamp, nonce, root information, difficulty level, consensus protocol, and/or other parameters or information associated with the corresponding files and/or the blockchain in general.

The files 774 ₂ to 774 _(N) in the other blocks may be equal to the original file or may be a modified version of the original file in the genesis block depending, for example, on the type of processing performed. The type of processing performed may vary from block to block. The processing may involve, for example, any modification of a file in a preceding block, such as redacting information or otherwise changing the content of, taking information away from, or adding or appending information to the files.

Additionally, or alternatively, the processing may involve merely copying the file from a preceding block, changing a storage location of the file, analyzing the file from one or more preceding blocks, moving the file from one storage or memory location to another, or performing action relative to the file of the blockchain and/or its associated metadata. Processing which involves analyzing a file may include, for example, appending, including, or otherwise associating various analytics, statistics, or other information associated with the file.

The values in each of the other blocks 776 ₂ to 776 _(N) in the other blocks are unique values and are all different as a result of the processing performed. For example, the value in any one block corresponds to an updated version of the value in the previous block. The update is reflected in the hash of the block to which the value is assigned. The values of the blocks therefore provide an indication of what processing was performed in the blocks and also permit a tracing through the blockchain back to the original file. This tracking confirms the chain-of-custody of the file throughout the entire blockchain.

For example, consider the case where portions of the file in a previous block are redacted, blocked out, or pixelated in order to protect the identity of a person shown in the file. In this case, the block including the redacted file will include metadata associated with the redacted file, e.g., how the redaction was performed, who performed the redaction, timestamps where the redaction(s) occurred, etc. The metadata may be hashed to form the value. Because the metadata for the block is different from the information that was hashed to form the value in the previous block, the values are different from one another and may be recovered when decrypted.

In one embodiment, the value of a previous block may be updated (e.g., a new hash value computed) to form the value of a current block when any one or more of the following occurs. The new hash value may be computed by hashing all or a portion of the information noted below, in this example embodiment.

-   -   a) new SHA-2 computed hash value if the file has been processed         in any way (e.g., if the file was redacted, copied, altered,         accessed, or some other action was taken)     -   b) new storage location for the file     -   c) new metadata identified associated with the file     -   d) transfer of access or control of the file from one blockchain         participant to another blockchain participant

FIG. 7D illustrates an embodiment of a block which may represent the structure of the blocks in the blockchain 790 in accordance with one embodiment. The block, Block_(i), includes a header 772 ₁, a file 774 ₁, and a value 776 ₁.

The header 772 ₁ includes a hash value of a previous block Block_(i-1) and additional reference information, which, for example, may be any of the types of information (e.g., header information including references, characteristics, parameters, etc.) discussed herein. All blocks reference the hash of a previous block except, of course, the genesis block. The hash value of the previous block may be just a hash of the header in the previous block or a hash of all or a portion of the information in the previous block, including the file and metadata.

The file 774 ₁ includes a plurality of data, such as Data 1, Data 2, . . . , Data N in sequence. The data are tagged with metadata Metadata 1, Metadata 2, . . . , Metadata N which describe the content and/or characteristics associated with the data. For example, the metadata for each data may include information to indicate a timestamp for the data, process the data, keywords indicating the persons or other content depicted in the data, and/or other features that may be helpful to establish the validity and content of the file as a whole, and particularly its use a digital evidence, for example, as described in connection with an embodiment discussed below. In addition to the metadata, each data may be tagged with reference REF₁, REF₂, . . . REF_(N) to a previous data to prevent tampering, gaps in the file, and sequential reference through the file.

Once the metadata is assigned to the data (e.g., through a smart contract), the metadata cannot be altered without the hash changing, which can easily be identified for invalidation. The metadata, thus, creates a data log of information that may be accessed for use by participants in the blockchain.

The value 776, is a hash value or other value computed based on any of the types of information previously discussed. For example, for any given block Block_(i), the value for that block may be updated to reflect the processing that was performed for that block, e.g., new hash value, new storage location, new metadata for the associated file, transfer of control or access, identifier, or other action or information to be added. Although the value in each block is shown to be separate from the metadata for the data of the file and header, the value may be based, in part or whole, on this metadata in another embodiment.

Once the blockchain 770 is formed, at any point in time, the immutable chain-of-custody for the file may be obtained by querying the blockchain for the transaction history of the values across the blocks. This query, or tracking procedure, may begin with decrypting the value of the block that is most currently included (e.g., the last (N^(th)) block), and then continuing to decrypt the value of the other blocks until the genesis block is reached and the original file is recovered. The decryption may involve decrypting the headers and files and associated metadata at each block, as well.

Decryption is performed based on the type of encryption that took place in each block. This may involve the use of private keys, public keys, or a public key-private key pair. For example, when asymmetric encryption is used, blockchain participants or a processor in the network may generate a public key and private key pair using a predetermined algorithm. The public key and private key are associated with each other through some mathematical relationship. The public key may be distributed publicly to serve as an address to receive messages from other users, e.g., an IP address or home address. The private key is kept secret and used to digitally sign messages sent to other blockchain participants. The signature is included in the message so that the recipient can verify using the public key of the sender. This way, the recipient can be sure that only the sender could have sent this message.

Generating a key pair may be analogous to creating an account on the blockchain, but without having to actually register anywhere. Also, every transaction that is executed on the blockchain is digitally signed by the sender using their private key. This signature ensures that only the owner of the account can track and process (if within the scope of permission determined by a smart contract) the file of the blockchain.

FIG. 8 illustrates an example system 800 that supports one or more of the example embodiments described and/or depicted herein. The system 800 comprises a computer system/server 802, which is operational with numerous other general purpose or special purpose computing system environments or configurations. Examples of well-known computing systems, environments, and/or configurations that may be suitable for use with computer system/server 802 include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments that include any of the above systems or devices, and the like.

Computer system/server 802 may be described in the general context of computer system-executable instructions, such as program modules, being executed by a computer system. Generally, program modules may include routines, programs, objects, components, logic, data structures, and so on that perform particular tasks or implement particular abstract data types. Computer system/server 802 may be practiced in distributed cloud computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed cloud computing environment, program modules may be located in both local and remote computer system storage media including memory storage devices.

As shown in FIG. 8, computer system/server 802 in cloud computing node 800 is shown in the form of a general-purpose computing device. The components of computer system/server 802 may include, but are not limited to, one or more processors or processing units 804, a system memory 806, and a bus that couples various system components including system memory 806 to processor 804.

The bus represents one or more of any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnects (PCI) bus.

Computer system/server 802 typically includes a variety of computer system readable media. Such media may be any available media that is accessible by computer system/server 802, and it includes both volatile and non-volatile media, removable and non-removable media. System memory 806, in one embodiment, implements the flow diagrams of the other figures. The system memory 806 can include computer system readable media in the form of volatile memory, such as random-access memory (RAM) 810 and/or cache memory 812. Computer system/server 802 may further include other removable/non-removable, volatile/non-volatile computer system storage media. By way of example only, storage system 814 can be provided for reading from and writing to a non-removable, non-volatile magnetic media (not shown and typically called a “hard drive”). Although not shown, a magnetic disk drive for reading from and writing to a removable, non-volatile magnetic disk (e.g., a “floppy disk”), and an optical disk drive for reading from or writing to a removable, non-volatile optical disk such as a CD-ROM, DVD-ROM or other optical media can be provided. In such instances, each can be connected to the bus by one or more data media interfaces. As will be further depicted and described below, memory 806 may include at least one program product having a set (e.g., at least one) of program modules that are configured to carry out the functions of various embodiments of the application.

Program/utility 816, having a set (at least one) of program modules 818, may be stored in memory 806 by way of example, and not limitation, as well as an operating system, one or more application programs, other program modules, and program data. Each of the operating system, one or more application programs, other program modules, and program data or some combination thereof, may include an implementation of a networking environment. Program modules 818 generally carry out the functions and/or methodologies of various embodiments of the application as described herein.

As will be appreciated by one skilled in the art, aspects of the present application may be embodied as a system, method, or computer program product. Accordingly, aspects of the present application may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects of the present application may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.

Computer system/server 802 may also communicate with one or more external devices 820 such as a keyboard, a pointing device, a display 822, etc.; one or more devices that enable a user to interact with computer system/server 802; and/or any devices (e.g., network card, modem, etc.) that enable computer system/server 802 to communicate with one or more other computing devices. Such communication can occur via I/O interfaces 824. Still yet, computer system/server 802 can communicate with one or more networks such as a local area network (LAN), a general wide area network (WAN), and/or a public network (e.g., the Internet) via network adapter 826. As depicted, network adapter 826 communicates with the other components of computer system/server 802 via a bus. It should be understood that although not shown, other hardware and/or software components could be used in conjunction with computer system/server 802. Examples, include, but are not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method, and non-transitory computer readable medium has been illustrated in the accompanied drawings and described in the foregoing detailed description, it will be understood that the application is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions as set forth and defined by the following claims. For example, the capabilities of the system of the various figures can be performed by one or more of the modules or components described herein or in a distributed architecture and may include a transmitter, receiver or pair of both. For example, all or part of the functionality performed by the individual modules, may be performed by one or more of these modules. Further, the functionality described herein may be performed at various times and in relation to various events, internal or external to the modules or components. Also, the information sent between various modules can be sent between the modules via at least one of: a data network, the Internet, a voice network, an Internet Protocol network, a wireless device, a wired device and/or via plurality of protocols. Also, the messages sent or received by any of the modules may be sent or received directly and/or via one or more of the other modules.

One skilled in the art will appreciate that a “system” could be embodied as a personal computer, a server, a console, a personal digital assistant (PDA), a cell phone, a tablet computing device, a smartphone or any other suitable computing device, or combination of devices. Presenting the above-described functions as being performed by a “system” is not intended to limit the scope of the present application in any way but is intended to provide one example of many embodiments. Indeed, methods, systems and apparatuses disclosed herein may be implemented in localized and distributed forms consistent with computing technology.

It should be noted that some of the system features described in this specification have been presented as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very large-scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, graphics processing units, or the like.

A module may also be at least partially implemented in software for execution by various types of processors. An identified unit of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions that may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module. Further, modules may be stored on a computer-readable medium, which may be, for instance, a hard disk drive, flash device, random access memory (RAM), tape, or any other such medium used to store data.

Indeed, a module of executable code could be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network.

It will be readily understood that the components of the application, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the embodiments is not intended to limit the scope of the application as claimed but is merely representative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that the above may be practiced with steps in a different order, and/or with hardware elements in configurations that are different than those which are disclosed. Therefore, although the application has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent.

While preferred embodiments of the present application have been described, it is to be understood that the embodiments described are illustrative only and the scope of the application is to be defined solely by the appended claims when considered with a full range of equivalents and modifications (e.g., protocols, hardware devices, software platforms etc.) thereto. 

What is claimed is:
 1. A system, comprising: a blockchain network, comprising: a smart contract, comprising a stored smart contract identifier; and a committer node or peer, configured to process blocks of transactions, the committer node or peer further configured to: receive a block comprising a lock request that locks a partial state of the smart contract, the lock request comprising a submitter identifier and a lock delay; validate the lock request; commit transactions comprising the submitter identifier with no delay; and commit transactions not comprising the submitter identifier after the lock delay.
 2. The system of claim 1, wherein the lock request comprises the submitter identifier, a lock smart contract identifier, one or more keys, and the lock delay, wherein the lock delay comprises a number of blocks.
 3. The system of claim 2, wherein the committer node or peer validates the lock request comprises the committer node or peer configured to: verify with the one or more keys that the lock request was submitted by a valid client or node of the blockchain network; verify the lock smart contract identifier matches the stored smart contract identifier; verify the submitter identifier applies to a client or node allowed to submit a lock request for the smart contract; determine a different lock request is not currently active for the smart contract; and in response to the committer node or peer determines the different lock request for the smart contract is currently active, the committer node or peer is configured to: reject the lock request.
 4. The system of claim 2, wherein in response to the committer node or peer receives a blockchain transaction for the block that applies to the smart contract, the committer node or peer is further configured to: commit the blockchain transaction to the block without further validation, in response to no active lock request for the smart contract; invalidate and do not commit the blockchain transaction, in response to the blockchain transaction for the smart contract was submitted by a node or peer that does not match the submitter identifier; and commit the blockchain transaction to the block, in response to an active lock request for the smart contract was submitted by a node or peer that matches the submitter identifier.
 5. The system of claim 2, wherein the lock request upgrades a previous lock request in response to the submitter identifier matches a submitter identifier for the previous lock request, wherein the lock request is rejected in response to the submitter identifier does not match the submitter identifier for the previous lock request.
 6. The system of claim 2, wherein the lock request is released after one of a blockchain transaction for the smart contract is committed to the blockchain or in response to a blockchain transaction for the smart contract comprises an instruction to release the lock.
 7. The system of claim 2, wherein the lock request expires in response to one of a specific time for lock expiry or a number of blocks the lock request is active within the lock request.
 8. A method, comprising: receiving, by a committer node or peer of a blockchain network, a block comprising a lock request that locks a partial state of a smart contract, the lock request comprising a submitter identifier and a lock delay, the committer node or peer configured to process blocks of transactions, the method further comprising: validating the lock request; committing transactions comprising the submitter identifier with no delay; and committing transactions not comprising the submitter identifier after the lock delay.
 9. The method of claim 8, wherein the lock request comprises a submitter identifier, a lock smart contract identifier, one or more keys, and the lock delay, wherein the lock delay comprises a number of blocks.
 10. The method of claim 9, wherein validating the lock request comprising: verifying using the one or more keys, by the committer node or peer, that the lock request was submitted by a valid client or node of the blockchain network; verifying the lock smart contract identifier matches a stored smart contract identifier for the smart contract; verifying the submitter identifier applies to a client or node allowed to submit a lock request for the smart contract; determining a lock request is not currently active for the smart contract; and in response to the committer node or peer determining a previous lock request for the smart contract is currently active, the method further comprising: rejecting the lock request.
 11. The method of claim 9, further comprising: receiving, by the committer node or peer, a blockchain transaction for the block that applies to the smart contract, and in response: committing the blockchain transaction to the block without further validating, in response to no active lock request for the smart contract; invalidating and not committing the blockchain transaction, in response to the blockchain transaction for the smart contract was submitted by a node or peer that does not match the submitter identifier; and committing the blockchain transaction to the block, in response to an active lock request for the smart contract was submitted by a node or peer that matches the submitter identifier.
 12. The method of claim 9, further comprising: matching the submitter identifier to a submitter identifier for the previous lock request, and in response: upgrading a previous lock request; and not matching the submitter identifier to the submitter identifier for the previous lock request, and in response: rejecting the lock request.
 13. The method of claim 9, further comprising: releasing the lock request in response to one of: committing a blockchain transaction for the smart contract to the blockchain; or in response to a blockchain transaction for the smart contract comprising an instruction to release the lock.
 14. The method of claim 9, wherein the lock request expires in response to one of a specific time for lock expiry or a number of blocks the lock request is active within the lock request.
 15. A non-transitory computer readable medium comprising instructions, that when read by a processor, cause the processor to perform: receiving, by a committer node or peer of a blockchain network, a block comprising a lock request that locks a partial state of a smart contract, the lock request comprising a submitter identifier and a lock delay, the committer node or peer configured to process blocks of transactions, the instructions causing the processor to further perform; validating the lock request; committing transactions comprising the submitter identifier with no delay; and committing transactions not comprising the submitter identifier after the lock delay.
 16. The non-transitory computer readable medium of claim 15, wherein the lock request comprises a submitter identifier, a lock smart contract identifier, one or more keys, and the synchronization delay, wherein the synchronization delay comprises a number of blocks.
 17. The non-transitory computer readable medium of claim 16, wherein validating the lock request comprising: verifying using the one or more keys, by the committer node or peer, that the lock request was submitted by a valid client or node of the blockchain network; verifying the lock smart contract identifier matches a stored smart contract identifier for the smart contract; verifying the submitter identifier applies to a client or node allowed to submit a lock request for the smart contract; determining a lock request is not currently active for the smart contract; and in response to the committer node or peer determining a previous lock request for the smart contract is currently active, the method further comprising: rejecting the lock request.
 18. The non-transitory computer readable medium of claim 16, further comprising: receiving, by the committer node or peer, a blockchain transaction for the block that applies to the smart contract, and in response: committing the blockchain transaction to the block without further validating, in response to no active lock request for the smart contract; invalidating and not committing the blockchain transaction, in response to the blockchain transaction for the smart contract was submitted by a node or peer that does not match the submitter identifier; and committing the blockchain transaction to the block, in response to an active lock request for the smart contract was submitted by a node or peer that matches the submitter identifier.
 19. The non-transitory computer readable medium of claim 16, further comprising: matching the submitter identifier to a submitter identifier for the previous lock request, and in response: upgrading a previous lock request; and not matching the submitter identifier to the submitter identifier for the previous lock request, and in response: rejecting the lock request.
 20. The non-transitory computer readable medium of claim 16, wherein the lock request expires in response to one of a specific time for lock expiry or a number of blocks the lock request is active within the lock request, wherein the method further comprising: releasing the lock request in response to one of: committing a blockchain transaction for the smart contract to the blockchain; or in response to a blockchain transaction for the smart contract comprising an instruction to release the lock. 